Comment #9 on issue 2026 by asmeurer: Exact, algebraic, and integer_power substitution
http://code.google.com/p/sympy/issues/detail?id=2026
The third case is a bit specific, but very important to making certain algorithms work, particularly integrate(). I need to find the blocking issues so you can see what I mean. Basically, you need the result to be a polynomial in the substitution term, so you have to avoid fractional exponents. The third case probably does need a better name than integer_powers btw.
If you insist on exact substitution being its own method, I think it should be called atomic_subs or something similar, since we decided expr.atomic_subs(old, new) should work if and only if old is in expr.atoms(old.__class__) (comment 1 above). I really don't see why it can't just be another hint to subs, though.
-- You received this message because you are subscribed to the Google Groups "sympy-issues" group. To post to this group, send email to sympy-issues@googlegroups.com. To unsubscribe from this group, send email to sympy-issues+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy-issues?hl=en.
